A group of researchers recently published a paper in the journal Scientific Reports that demonstrated the feasibility of using a novel graphene oxide-folic acid/silk fibroin (GO-FA/SF) nanobiocomposite in biomedical applications.
Study: Functionalized graphene oxide nanosheets with folic acid and silk fibroin as a novel nanobiocomposite for biomedical applications. Image Credit: Buravleva stock/Shutterstock.com
Importance of GO, FA, and SF for the Synthesis of Novel Nanobiomaterial
Graphene, a two-dimensional (2D) layered structure of carbon atoms, has gained considerable prominence owing to its exceptional chemical properties. Graphene analogs, such as GO and graphene nanosheets, are typically produced by functionalizing and modifying the carbon platform of graphene.
GO can be obtained through the Hummers method, where strong oxidizing agents such as concentrated sulfuric acid and potassium permanganate react with graphite to produce GO in the form of a yellow colloidal dispersion.
GO and its derivatives are suitable for different applications, such as skin-tissue and bone engineering and pH-dependent drug delivery. This is because of its unique properties, such as inhibition of bacterial growth, aqueous processability, and ability to synthesize stable colloidal suspensions.
The conductivity, tensile strength, and elasticity of GO can be further improved by combining it with natural or synthetic materials such as vitamins and polymers. FA, a water-soluble vitamin, is often used in biomaterials with potential bioapplications such as drug carriers and imaging systems due to its non-toxicity, biocompatibility, and low cost.
By functionalizing GO with FA through covalent bonds via the amidation process, biocompatible materials with an extensive range of bioapplications can be synthesized effectively.
SF, a well-known natural protein found in silkworms, has gained prominence as a potential candidate for scaffolds in tissue engineering and biomaterials owing to its significant biodegradability, biocompatibility, elasticity, and mechanical strength. Additionally, silk can be easily purified and isolated and has a low risk of infection. The GO-FA conjugate can be blended with SF through the freeze-drying process to fabricate a novel nanobiocomposite.
Nanobiomaterials have demonstrated significant potential in different applications such as pharmacology and nanomedicine. Although nanobiomaterials possess several advantages, they can cause biological side-effects such as an inflammatory reaction, which can eventually lead to cell death. Thus, the interactions and toxicity of these nanobiomaterials on the biological systems must be considered and evaluated before utilizing them in biological applications.
Synthesis of GO-FA/SF Nanobiocomposite
In this study, researchers synthesized a biocompatible and non-toxic novel GO-FA/SF nanobiocomposite and evaluated the feasibility of using the synthesized sample in bioapplications.
GO was synthesized from graphite flake through the modified Hummer method. 0.3 grams of 4-(dimethylamino) pyridine (DMAP) and 1.85 grams of N, N′-dicyclohexylcarbodiimide (DCC) were added to 0.5 grams of GO suspension in 100 milliliters of dimethyl sulfoxide (DMSO), and the resultant mixture was sonicated for 20 minutes to activate the terminal carboxyl and carbonyl groups of GO.
Subsequently, 0.3 grams of FA was mixed with the activated GO, and the mixture was again sonicated for 20 minutes and stirred overnight. The mixture was then centrifuged and washed with distilled water and ethanol to eliminate DSMO and nonconjugated FAs from the GO-FA. Eventually, the GO-FA mixture was washed using acetone and dried at room temperature to obtain GO-FA in a powder form.
SF was extracted from cocoons through degumming, rehydration, and dialysis steps. For a few minutes, 0.2 grams of GO-FA was sonicated in distilled water and then mixed with 5 milliliters of SF solution, and the mixture was kept under stirring conditions for four hours. Subsequently, the resultant suspension mixture was placed in a petri dish for the freeze-drying process. The sample was initially kept in a freezer at -70 degree Celsius for 24 hours and then in a freeze-dryer device for 24 hours to sublimate the solvent, followed by the dehydration process at -60 degree Celsius to obtain the GO-FA/SF nanobiocomposite.
Characterization and Evaluation of Synthesized Samples
Fourier-transform infrared (FT-IR) spectroscopy, field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) method, and thermogravimetric analysis (TGA) were used to characterize the synthesized samples. Researchers also performed anti-biofilm, 3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide (MTT), and hemolysis assays on Pseudomonas aeruginosa (P. aeruginosa), human skin fibroblast (Hu02) cells, and human red blood cells (RBCs), respectively, to evaluate the biological capability of the synthesized nanobiocomposite.
Research Findings
A novel GO-FA/SF nanobiocomposite was fabricated successfully using inexpensive and non-toxic starting materials. The FT-IR analysis confirmed the presence of hydroxyl, carboxyl, alcohol, alkoxy, and epoxy groups, as well as an unoxidized graphitic domain in the synthetic GO. Additionally, the analysis also confirmed the formation of an amide bond during the conjugation of FA with GO, and the presence of SF in the nanobiocomposite.
The modified GO in the GO-FA/SF nanobiocomposite demonstrated smooth unilamellar morphology while preserving the characteristic structure of the pure GO flakes. The GO-FA/SF degraded gradually with increasing temperatures, with the complete decomposition of the nanobiocomposite observed at 800 degrees Celsius.
The biological assays displayed exceptional features of the GO-FA/SF nanobiocomposite. The cell viability percentages were 97.23, 96.35, and 96.67% when Hu02 cells were treated with the synthesized nanobiocomposite for 72, 48, and 24 hours, respectively, and the cells maintained their fibroblast shape, indicating the non-toxicity and biocompatibility of the GO-FA/SF nanobiocomposite.
The hemolysis percentages for 72 and 24 hours of extraction time were less than 10%, which demonstrated the hemocompatibility of the synthesized nanobiocomposite. Moreover, the synthesized GO-FA/SF nanobiocomposite effectively inhibited the formation of P. aeruginosa biofilm on its surface.
Taken together, the findings of this study demonstrated that the synthesized GO-FA/SF nanobiocomposite can be used safely and effectively for different biomedical applications such as tissue engineering and wound healing.
Reference
Mahdavi, M., Madanchi, H., Maleki, A. et al. (2022) Functionalized graphene oxide nanosheets with folic acid and silk fibroin as a novel nanobiocomposite for biomedical applications. Scientific Reports. https://www.nature.com/articles/s41598-022-10212-0
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